Methods are known in the art for glass manufacturing wherein glass-forming, batch ingredients are compacted into agglomerates and then are heated in a chamber by a direct contact with flue gases from a glass melting furnace so as to produce free-flowing agglomerates which are then conveyed and discharged to the glass melting furnace. These agglomerates are composite, integral, self-supporting masses consisting essentially of all the substantial batch materials and may take the form of balls, extrusions, discs, briquettes, and pellets. The pellets are discharged to a vertical bed contained within a chamber and furnace flue gases pass, in direct contact with and countercurrently to, downwardly moving pellets of the bed to preheat them.
One method known in the art to form the agglomerates is to combine the glass forming batch ingredients with a liquid such as caustic or water. While most teachings of the prior art work well for many glass batch formulations, some teachings are entirely unsuitable for certain agglomerated glass batch formulations. This unsuitability is especially acute in instances of agglomerating certain glass batch formulations with water to form pellets.
In the context of drying and heating liquid-containing, glass batch agglomerates with flue gases from a fossil fuel fired melting furnace, the most desirable process equipment of the prior art is a shaft type heater, or chamber, i.e., a vertical bed of substantial height, and preferably a bed in which the agglomerates flow downwardly through the chamber and in which the flue gases flow countercurrent to the agglomerates, to substantially continuously, in a single processing operation, dry and preheat them.
Some glass batch agglomerates are, however, unstable and substantially continuous drying and heating in a single operation in a vertical bed is not obtainable. When such liquid-containing glass batch agglomerates are processed in direct contact with flue gases from a glass melting furnace, the wet agglomerate containing portion of the bed may aggregate into a strong, rather massive, monolithic type structure, or structures, which plug the shaft heater. This unacceptably necessitates shutdown.